Earnings Per Share - Reconciliation from Basic Earnings Per Share to Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2019	Nov. 30, 2018	Nov. 30, 2019	Nov. 30, 2018
Earnings Per Share [Abstract]
Net income available to common stockholders	$ 1,115	$ 847	$ 2,482	$ 1,939
Determination of shares:
Weighted average common shares outstanding	1,560.6	1,581.4	1,561.5	1,587.7
Assumed conversion of dilutive stock options and awards	33.8	39.3	34.5	39.5
DILUTED WEIGHTED AVERAGE COMMON SHARES OUTSTANDING	1,594.4	1,620.7	1,596.0	1,627.2
Earnings per common share:
Basic (in dollars per share)	$ 0.71	$ 0.54	$ 1.59	$ 1.22
Diluted (in dollars per share)	$ 0.70	$ 0.52	$ 1.56	$ 1.19